If you are like most people, you may well subscribe to the ONAAT fallacy. I am more confident, however, that you don’t know what it is. That’s because I just made up the name, although not the concept.

The ‘ONAAT’ fallacy stands for ‘one nutrient at a time.’ It’s the false, but insidiously persistent notion, that the nutritional quality of a food, or the relevant nutrition guidance for a given patient, can in fact be gauged just that way, one nutrient at a time.

Having devoted years of effort to the development of a nutrition guidance system that can function as ‘GPS for the food supply,’ providing summative information about overall nutritional quality — I find the proliferation of so-called “attribute systems” (e.g., this one, this one, and this one and others like them) that call out one or more attributes of a food a potential threat to progress in this area.

My physician colleagues are, with all due respect to our clan, a major reason the ONAAT fallacy was set in motion, and propagated. Because of relative neglect of nutrition in medical education, physicians tend to ignore the topic, or when addressing it at all, to offer limited and discrete advice directly related to their field.

Rather than providing advice about food, let alone the whole diet, cardiologists may be prone to advise against an excess of saturated and trans fat, and dietary cholesterol. Endocrinologists may emphasize avoidance of sugar and refined starches. Gastroenterologists may focus on fiber. Nephrologists and others treating high blood pressure may focus on sodium. And so on. There are exceptions, of course, but the rule prevails.

In my own primary care practice over the years, I have encountered many patients who were trying to follow exactly that kind of dietary advice, imparted by some medical specialist focusing on some particular condition or risk factor. The trouble with “one nutrient at a time” guidance is of the classic missing the forest for the trees variety, or of the even worse “mistaking the part for the elephant” variety. The nutritional properties of a food cannot reliably be captured in any given nutrient level or attribute.

A food may be a source of whole grain, but also a concentrated source of sugar and salt. A food may be low in sugar, but high in salt — or vice versa. A food may be low in sugar, but a delivery vehicle for trans fat. It may be trans fat free, because it is comprised entirely of sugar and food dyes. Such a food — gummy bears, for instance — may be organic, without that signifying anything commendable about its nutritional profile.

Food cannot be judged one component at a time any better than elephants can. What about health?

Here, the fallacy implicit in a one-attribute-at-a-time view of the world is even more obvious. A normal resting heart rate does not rule out multiple sclerosis. A cholesterol value in the desired range does not preclude HIV.

Being free of cancer does not mean good health in someone dying of emphysema. Being free of emphysema would provide scant comfort to someone with advanced pancreatic or ovarian cancer. Being free of cancer would not count as vitality in someone with severe heart failure, or cerebral malaria. Hardly anyone would take pleasure in the robust good health of the left side of their body, while the right side was bleeding profusely.

And then there is the relationship between diet and health, where the fallacy pertains just as well. True, someone with diabetes is well advised to be cautious about sugar, refined starch, and glycemic load. But diabetes, and the insulin resistance that precedes it, is very often accompanied by hypertension — so this group can’t neglect sodium.

And, the leading cause of death in diabetes is cardiovascular disease. So if trans fat and certain saturated fats are of concern in heart disease, they must be of concern in diabetes, and prediabetes, as well.

We know that inflammation is a major contributor to diabetes, heart disease, and cancer and the aging process itself — and that high levels of insulin can foster inflammation. So sugar, starch, and glycemic load are of concern across the board. Omega-3 fats can reduce inflammation, so they are beneficial to almost everyone.

Dietary fibers can lower blood pressure, and cholesterol, and insulin; can stabilize blood sugar; can improve gastrointestinal health, and potentially lower cancer risk; and can help produce satiety that facilitates weight control. So they are only important for anyone at risk for conditions that cumulatively affect … at least 80 percent of the entire population!

In short, you cannot use one nutrient at a time to protect one component of health at a time. You can, of course, use foods of high overall nutritional quality, making up a wholesome diet, as a potent defense against virtually all forms of ill health, and a pillar of vitality.

Good food is among the best medicines we have. Good nutrition, like good health, is best viewed holistically. So beware the ONAAT fallacy — because we are unlikely to get to either good food, or good health, one attribute at a time.